Apparatus for railway train communication systems



G. R. PFLASTERER Aug. 5, 1941.

APPARATUS FOR RAILWAY TRAIN COMMUNICATION SYSTEMS Filed Jan. 18, 1940 qIN NTOR Geargeg. Pf

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l/IS ATTORNEY Patented Aug. 5, 1941 APPARATUS FOR RAILWAY TRAINCOMMUNICATION SYSTEMS George R. Pflasterer, Greenville, Pa., assignor toThe Union Switch and SignalCompany, Swissvale, Pa., a corporation ofPennsylvania Application January 18, 1940, Serial No. 314,471

3 Claims.

My invention rela es to apparatus for railway train communicationsystems, and more particularly to apparatus for railway traincommunication systems which use the track rails as a part of thetransmitting circuit.

Railway train communication systems for telephone communication betweena station located on a vehicle of a train, such as a locomotive of afreight train, and another station remote therefrom, such as a stationlocated in the caboose of the freight train, are in use. Telephonecurrent is applied to the track rails at the sending location eitherinductively through the medium of an inductor mounted in inductiverelation with the rails or conductively through the medium of a circuitconnected with the rails. The current flows in the rails in bothdirections from the point at which it is applied and returns through theground and other conductors. At the receiving station current ispreferably received from the track rails inductively through the mediumof an inductor mounted in inductive relation with the rails. At a trackswitch connecting two diverging tracks, such communication current maydivide between the rails of the two possible routes. That portion of thecommunication current that flows in the rails of the track opposite thatset up by the position of the track switch may serve little or no usefulpurpose and hence may be a leakage current.

Accordingly, a feature of my invention is the provision of novel andimproved means for such train communication systems for routing thecommunication current to the track rails corresponding to the route setup for the train, so

that unnecessary division of the current is avoided. This feature, aswell as other advantages of my invention, I effect by locating insulatedrail joints at selected points in the track rails of each route leadingfrom a track switch to block the flow of communicaticn current and thenby-passing the current around the insulated rail joints in the track ofthe route set up by the track switch by a circuit network controlledaccording to the position of the track switch, such circuit networkbeing effective to by-pass the communication current around theinsulated joints with little or no attenuation and to effectively blocktrack circuit current used for signaling.

I shall describe two forms of apparatus embodying my invention and shallthen point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view showing oneform of apparatus embodying my invention when used at a track switch ina non-track circuited territory, and Fig. 2 is a diagrammatic viewshowing a preferred form of apparatus embodying my invention when usedat a track switch in a territory provided with track circuits.

In each of the different views like reference characters designatesimilar parts.

Referring to Fig. 1, the reference characters Ia and lb designate thetrack rails of a first or main track PI of a stretch of railway whichincludes a track switch SW of a turnout leading to a second track S'Ithe rails of which second track are designated by the referencecharacters to and Id. In accordance with standard prac- :e, the trackswitch SW when set at its normal position, that is, the position shownin Fig. 1, establishes the route for trains on the main track. In otherwords, when the track switch SW is set at its normal position a trainwill pass from the left-hand portion of the track FT to the righthandportion or vice versa. When the track switch is set at its reverseposition, that is, the position opposite that shown in Fig. 1, a routefor trains to pass from track FT to track ST or vice versa isestablished. As stated hereinbefore, the tracks FT and ST of Fig. 1 arenot provided with track circuited sections for signaling. However, thetrack rails of each or the two tracks FT and ST of Fig. 1 may be bondedin any one of the well-known ways to form the rails into continuouselectrical conductors as an aid in transmitting the communicationcurrent. Such bonding of the track rails may not be needed, thefastenings of the rail joints serving to electrically join the adjacentrails. A pair of insulated rail joints 4 and 5 is placed in the track FTat a selected point preferably in the vicinity of the frog of theturnout, rail joint 4 being placed in rail Ia. and rail joint 5 beingplaced in rail lb. Preferably a cross bond 6 electrically connects therails la and lb together at the left-hand side of the insulated railjoints 4 and 5 and a cross bond 1 connects the rails together at theright-hand side of the insulated rail joints. In a similar manner a pairof insulated rail joints 8 and 9 is placed in track ST at a selectedpoint, preferably in the vicinity of the frog of the turnout, rail joint'8 being placed in rail la and rail joint 9 being placed in rail Id.Also, two cross bonds I0 and H are preferably connected across the railslc and Id on opposite sides respectively of the insulated rail joints 8and 9.

-A switch circuit controller SC is operatively connected with the trackswitch SW as indicated by a dotted line for operation of two circuitcontrolling contacts [2 and is, the arrangement being such that contactsi2 and I3 occupy the positions indicated by the solid lines when theswitch SW is set at its normal position and are moved upward as viewedin the drawing to the dotted line positions when the switch is set atits reverse position. The contact [2 is included in a circuit forbridging the insulated rail joints 4 and 5, such circuit comprising wire[4 connected to rail lb to the right of insulated rail joint 5, contacti 2 closed at the normal position of switch SW and wire l5 connected torail id to the left of insulated rail joint 4. Since cross bonds 6 and lelectrically connect the rails la and lb together it is clear that thiscircuit, including contact i2, bridges around both insulated rail joints4 and 5. The contact [3 is included in a circuit for bridging theinsulated rail joints 8 and 9, the circuit comprising wire i6 connectedto rail Id to the right of the insulated rail joint 9, contact it?closed when the switch SW is set at its reverse position and wire I?connected to rail lc to the left of the insulated rail joint 8. Sincethe cross bonds Iii and Ii electrically connect the rails lo and idtogether it is clear that this circuit, including contact i3 bridgesaround both insulated rail joints 8 and 9 when the switch SW is set atits reverse position.

It follows that when track switch SW is set at its normal position toestablish the route on the main track FT, insulated rail joints 4 and 5are bridged by the associated circuit and communication current isby-passed around the tion to establish the route to track ST, insulatedrail joints 8 and 9 are bridged by the associated circuit to by-pass thecommunication current around such insulated joints, while the insulatedjoints 4 and 5 are effective to block the flow of.

communication current in the track FT.

In Fig. 1 a train shown conventionally at TV includes a locomotiveindicated at LC and a caboose indicated at CB. Telephone stations Si andS2 are located on the locomotive LC and in the caboose CB, respectively.Each station Si and S2 is provided with transmitting and receivingtelephone apparatus of any one of the several well-known forms and suchapparatus will be described in the present application only insofar asis necessary to fully understand the present invention. The apparatusesat the two stations Si and S2 are preferably alike and hence adescription of one will serve for an understanding of both.

Looking at station Si, the input winding 18 of a transformer Ti isconnected with an inductor i9 mounted on the locomotive in thewell-known manner in inductive relation with the track rails. The outputwinding 2i of transformer Ti is connected with the input terminals of areceiving amplifier EA to whose output terminals a telephone receiver orloud speaker 2i] is connected. The receiving amplifier RA is shownconventionally since its specific structure forms no part of m presentinvention and it may be any one of the several well-known forms for suchamplifier. The output winding 22 of a transformer T2 is conductivelycoupled with the track rails over wires 23 and 24 due to these wiresbeing connected with different axles of the locomotive in any of theseveral well-known ways. The input winding 25 of transformer T2 isconnected with the output terminals of a sendin amplifier SA to whoseinput terminals a microphone 26 is connected. The amplifier SA may besimilar to the amplifier RA. It is clear that voice frequencies producedby speaking into the microphone 25 are amplified at the amplifier SA andare applied to the rails adjacent the locomotive, from which point thetelephone current flows in the rails in multiple in both directions inthe well-known manner, a portion of the telephone current reaching theremote station S2. When telephone current is applied in a similar mannerto the rails at the remote station and a portion flows in the railsadjacent the locomotive LC such telephone current induces correspondingelectromotive forces in the inductor i9 which in turn are applied to theamplifier RA causing the voice frequencies of the telephone current tobe reproduced at the loud speaker 25, It will be understood, of course,that station Si includes proper circuit switching apparatus so that itsreceiving apparatus is not eifected by the telephone current sent out bythe same station.

With switch SW set at its normal position and the train TV occupyingthetrackFTin the position shown in Fig. 1, it is clear that thetelephone current applied to the rails by one of the stations, say, forexample, station S2 in the caboose, will flow in the rails past thetrack switch SW to the locomotive LC by being by-passed around theinsulated rail joints 4 and 5 by the circuit completed at contact i2 ofthe switch circuit controller, and such communication current will beblocked from the rails of the track ST by the insuiated rail joints 8and 9. Likewise, telephone current transmitted from station Si will bebypassed around the insulated rail joints 4 and 5 and will be blockedfrom flowing in the rails of the track ST by the insulated rail joints 8and 9.

In the event the track switch SW is set at its reverse position so thatthe locomotive LC of train TV would occupy the track ST instead of trackFT, the telephone current transmitted from the caboose station S2 isby-passed around the insulated rail joints 8 and 9 by the circuitcompleted by the contact i 3 of the switch circuit controller and thetelephone current is blocked from flowing in the rails of the track FTby the insulated rail joints 4 and 5.

Referring to Fig, 2, a turnout including a track switch SW connects amain track FT with a second track ST the same as in Fig. 1. In Fig. 2the track rails of each of the two tracks FT and ST are formed intotrack circuited' sections for signaling, only the one full section D-Ewhich includes the turnout together with parts of the adjoining sectionsbeing shown for the sake of simplicity since these are sufiicient for afull understanding of my invention. The limits of section D-E aredefined by a pair of insulated rail joints 39 and 3| placed in rails Iaand lb, respectively, to form the entrance end of the section and by asecond pair of insulated rail joints 32 and 33 placed in the rails laand lb, respectively, to define the exit end of the section, theinsulated joints 32 and 33 being preferably located in the vicinity ofthe switch frog at about the fouling point between the two tracks FT andST. Since the track switch SW is located in section DE the switch rodsof the switch points are insulated in the usual manner as indicated at34. Also insulated rail joints 36 and 31 are located in the lead railsof the turnout, insulated rail joints 38 and 39 are placed in rails loand Id, of track ST in the vicinity of the switch frog at about thefouling'point of the turnout and a cross bond 40 is connected betweenthe two outside rails la and Id so that the rails of the turnout areincluded in the track circuit of section DE in the usual manner.

The track circuit of section DE includes a source of current such as abattery 4I connected across the rails at the exit end of the section anda track relay TR connected across the rails at the entrance end of thesection, the track relay TR being used to control any desired form ofwayside signal not shown since such signal forms no part of myinvention.

In a similar fashion the track circuit for the section of track FT nextto the right of section DE includes a track battery 45 connected acrossthe rails adjacent location E. Also theftrack circuit for the sec-tionof track ST next tothe right of section DE includes a track battery 49connected across the rails at the right-hand side of insulated railjoints 38 and 39,

To provide a circuit for by-passing communication current aroundinsulated rail joints 32 and 33 and at the same time not interfere withthe track circuits of the respective sections, I provide a circuitnetwork controlled by circuit controller SC connected with the trackswitch SW the same as in Fig. 1. This circuit network involves a firstpath including wire 42 connected with rail Ia. to the left of theinsulated rail joint 32, a resistor RI, contact l2 of the switch circuitcontroller SC closed at the normal position of the track switch SW, aresistor R2 and wire 43 connected with rail Ia to the right of theinsulated rail joint 32. This circuit network also includes another paththat can be traced from rail lb over wire 53 comiected with rail lb justto the left of insulated rail joint 33, a resistor R3, contact I2, aresistor R4 and wire 44 connected to rail lb just to the right ofinsulated rail joint 33. It is clear that the rails I a and ID to theleft of the insulated rail joints 32 and 33 are connected togetherthrough wire 42, resistors RI and R3 in series and wire53; and theserails are connected together to the right of the joints 32 and 33 overwire 43, resistors R2 and R4 in series and wire 44. The resistors RI andR3 taken in series form a resistance sufficient to not seriouslyinterfere with track circuit of section DE. Likewise the resistors R2and R4 taken in series form a resistance suiiicient to not seriouslyinterfere with the track circuit of the section next to the right ofsection DE.

When the track switch SW is moved to its reverse position to set up theroute to track ST the insulated rail joints 38 and 39 are bridged by acircuit network. Starting from rail Id to the left of the insulated railjoint 39 a circuit path can be traced over cross bond 40, rail Ia, wire42, resistor RI, wire 46, contact I3 of switch circuit controller SCclosed at the reverse position of the track switch SW, a resistor R andwire 41 to rail Id to the right of insulated rail joint 39. Also,starting from rail Ic to the left of insulated rail joint 38 a circuitpath can be traced over rail l c to the switch frog, back on rail lb,wire 53, resistor R3, wire 46, contact I3, a resistor R6 and wire 48 torail I c to the right of the insulated rail joint 38.

Resistors R5 and R6 when taken in series form a circuit path across therails lo and Id to the right of the insulated rail joints 38 and 39 andthese two resistors in series form a resistancezof suflicie'nt magnitudeto not seriously interfere with the track circuit of the associatedtrack section. a a

In Fig. 2, a train TV provided with twotelephone stations SI and S2 isshown as moving on the track FT, the same as in Fig. 1. It is clear thattelephone current supplied to the track rails Ia and lb at station S2 isby-passed around the insulated rail joints 32 and 33 by the circuit"network completed by contact I2 of the switch circuit controller andsuch communication current is available for effectively operating thereceiving apparatus on the locomotive LC. Such telephone current isblocked from flowing in the rails of track ST because the circuitnetwork provided for bridging around the insulated rail joints 38'and 39is open at the contact I3 of the switch circuit controller. It is to benoted thatin the circuit network which by-passes the telephone currentaround the insulated rail joints 32 and 33; the resistors Rl and R3function in multiple and resistors R2 and R4 function in multiplebecause the mid terminal of resistors RI and R3 is connected with themid terminal of resistors R2 and R4. Likewise telephone current sent outby the station SI flows in the rails lb and la around the insulated rai1joints 32 and 33 by this circuit network completed by contact I2 of theswitch circuit controller.

In the event the track switch SW is set at its reverseposition and thelocomotive LC of train TV- of Fig. 2 is operating on track ST, thetelephone current supplied by either station SI or S2 is by-passedaround the insulated rail joints 38 and 39 by the circuit networkcompleted by contact I3 of the switch circuit controller and suchcurrent is blocked from the rails of the track FT by the insulated rai1joints 32 and 33. In this circuit network bridging rail joints 38 and 39it is to be observed that the resistors RI and R3 function in multipleand resistors R5 and R6 function in multiple because the contact l3connects the mid terminal of resistors RI and R3 with the mid terminalof resistors R5 and. R6.

While in the form of the invention here 'disclosed resistors are used inthe circuit network, it is clear that these resistors may be replaced"by other impedance devices such as condensers if desired, suchcondensers being proportioned to pass the telephone current and to blockthe flow of the track circuit current.

Furthermore, while only a single turnout is illustrated other and morecomplicated track layouts comprising crossovers and other track switchesmay be provided in a similar manner with circuit networks for routingthe communication current to the route set up by the track switches.

Although I have herein shown and. .7 described only two forms ofapparatus for railway train communication systems embodying myinvention, it is understood that various changes and modifications maybe made therein within the scope of the appended claims Withoutdeparting from the spirit and scope of my invention.

Havin thus described my invention, what I claim is:

1. In a train communication system for communication between a stationlocated on a vehicle of a train and a remote station by transmission ofcommunication current between the two stations over a transmittingcircuit including the track rails, the combination comprising, a turnoutto at times route a train from a main track to a second track and atleast the main track of which tracks is provided with a track circuitincluding the turnout, a switch circuit controller operatively connectedwith the track switch of said turnout for operation to a first or asecond position according as said track switch is set for the main trackor for said second track, a first pair of insulated rail joints placedin said main track with one joint in each rail back of the frog of saidturnout to block the fiow of said communication current, a second pairof insulated rail joints placed in said second track with one joint ineach rail back of the frog of said turnout to block the flow of saidcommunication current, a first and a second resistor connected in seriesacross the rails to one side of said first pair of insulated railjoints, a third and a fourth resistor connected in series across therails at the other side of said first pair of insulated rail joints, anda first position contact of said switch circuit controller to connectthe mid terminal of said first and second resistors with the midterminal of said third and fourth resistors to by-pass saidcommunication current around said first pair of insulated rail jointswhen the track switch is set for the main track.

2. In a train communication system for communication between a stationlocated on a vehicle of a train and a remote station by transmission ofcommunication current between the two stations over a transmittingcircuit including the track rails, the combination comprising, a turnoutto at times route a train from a main track to a second track, a trackcircuited insulated track section including a portion of said main trackand said turnout and having a first pair of insulated rail jointslocated in the rails of the main track at the fouling point of saidtracks and a second pair of insulated rail joints located in the railsof the second track at the fouling point, a switch circuit controlleroperatively connected with the track switch of said turnout foroperation to a first or a second position according as the track switchis set for the main track or for the second track, a first circuitnetwork including a first position contact of said switch circuitcontroller and impedances, said first circuit network connected acrossthe rails of the main track to each side of said first pair of insulatedrail joints and arranged to by-pass said communication current aroundsaid first pair of insulated joints and to effectively block the flow ofthe track circuit current when the track switch is set for the maintrack, and a second circuit network including a second position contactof said switch circuit controller and impedances, and said secondcircuit network connected across the rails to each side of said secondpair of insulated rail joints, and arranged to by-pass saidcommunication current around said second pair of insulated rail jointsand effectively block the flow of the track circuit current when thetrack switch is set for the second track.

3. In a train communication system for communication between a stationlocated on a vehicle of a train and a remote station by transmission ofcommunication current between the two stations over a transmittingcircuit including the track rails, the combination comprising, a turnoutto at times route a train from a main track to a second track, atrack-circuited insulated track section including a portion of said maintrack and said turnout and having a first pair of insulated rail jointslocated in the rails of the main track at the fouling point of saidtracks and a second pair of insulated rail joints located in the railsof the second track at the fouling point, a switch circuit controlleroperatively connected with the track switch of said turnout foroperation to a first or a second position according as the track switchis set for the main track or for the second track, a first circuitnetwork including a first position contact of said switch circuitcontroller and four resistances, said first circuit network arrangedwith two of its resistances connected in series across the railsadjacent one side of said first pair of insulated rail joints and itsother two resistances connected in series across the rails adjacent theother side of said first pair of joints and its first position contactconnecting the mid terminal of the first two mentioned resistances withthe mid terminal of the last two mentioned resistances whereby saidfirst circuit network is efiective to by-pass said communication currentaround said first pair of insulated rail joints without interference tothe track .circuit when the track switch is set for the main track, anda second circuit network including a second position contact of saidswitch circuit controller and two resistances, and said second circuitnetwork arranged with its resistances connected in series across therail adjacent said second pair of insulated rail joints on the sideremote from the track switch and its second position contact connectedbetween the mid terminal of its two resistances and the mid terminal ofthe first two mentioned resistances of said first circuit networkwhereby said second circuit network is effective to by-pass saidcommunication current around said second pair of insulated rail jointswithout interference to the track circuit when the track switch is setfor the second track.

GEORGE R. PFLASTERER.

